Objectives of this research are to discover, classify and investigate cognitive functions of aging which are non-declining or incremental. The method employs a modified version of the Critical Incident Technique to provide objective data, based on interviews with older adults in two widely separated geographic areas, to identify and classify cognitive functions. Based on analysis of the data thus obtained, refinement and definition by specific incidents are planned to produce items representative of incremental cognitive functions in aging. Investigation of relative frequencies and estimates of reliability across and within demographic and socio-economic variation is planned to produce a preliminary instrument, for assessment of incremental cognitive functions, suitable for further evaluation, on an experimental basis. The aim of the research is to focus more clearly on cognitive functions not now tapped or vaguely defined by current tests of intelligence and related functions.